NestJS FilesInterceptor breaks tracing

[nilswinking]

What happened?

When using the FilesInterceptor in a NestJS application tracing does not work.

Steps to Reproduce

Reproduction: https://stackblitz.com/edit/nestjs-otel-tracing-files-interceptor?file=src%2Fapp.controller.ts

1. Start the project.
2. Send a request to /, you will see the tracing output in the console.
3. Comment out the @UseInterceptors(FilesInterceptor('files')) part.
4. Once the application restarted with the changes send another request.

Expected Result

Tracing output is visible in the console

Actual Result

No tracing output is visible/no tracing is happening

Additional Details

• The mere presence of this annotation is enough to break tracing. The issue is not limited to the one endpoint annotated with it
• Other Interceptors can be used without issue. I have included a LoggingInterceptor in the reproduction to check.
• I have checked with both node 18 and 20, but the reproduction is using version 18
• the reproduction uses SimpleSpanProcessor and ConsoleSpanExporter but BatchSpanProcessor and other exporters also don't work

OpenTelemetry Setup Code

package.json

Relevant log output

Operating System and Version

No response

Runtime and Version

Node.js v18.20.3 and Node.js v20.18.2

[mehdifracso]

OtelSDK needs to be imported before everything so it patches every module before they're loaded.

Here is how I fixed it, I moved the otelSDK import to the top of the main.ts file:

import otelSDK from './tracing';
import { NestFactory } from '@nestjs/core';
import { AppModule } from './app.module';
// import otelSDK from './tracing';

async function bootstrap() {
  otelSDK.start();
  const app = await NestFactory.create(AppModule);
  await app.listen(3000);
}
bootstrap();

[dyladan]

@nilswinking does the above suggestion fix your issue?

[nilswinking]

I ended up having to use a dynamic import as having some other imports before the initialization caused some other problems.

import otelSDK from '@app/utils/tracing';

async function bootstrap() {
  otelSDK.start();
  await import('./server').then(async ({ startServer }) => {
    await startServer();
  });
}

bootstrap();